The Graeae/Stygian Witches.

There was no “kraken” in Greek mythology, but Desmond Davis’ 1981 smash Clash of the Titans had such a following, and the phrase “Release the Kraken” (uttered by Sir Laurence Olivier) was so hugely popular, that the remake needed it. And it was fun. http://qilong.deviantart.com/art/Whale-of-a-Tail-405908478